Compilare: user.cpp: In member function ‘bool TrieNode::hasSons(int)’: user.cpp:26:80: warning: NULL used in arithmetic [-Wpointer-arith] if( (this->sons[i]->NrWord)>0 || (this->sons[i]->hasSons(-1))!=NULL ) ^ user.cpp: In function ‘int main()’: user.cpp:111:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("trie.in", "r", stdin); ^ user.cpp:112:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("trie.out", "w", stdout); ^